1. Field of the Invention
This invention relates to a color liquid-crystal display (LCD) panel and a manufacturing process thereof. In particular, it relates to a color liquid-crystal display panel comprising a switching element such as a thin-film transistor (TFT), a color filter, and a black matrix on a single substrate.
2. Description of the Related Art
In general, a thin film transistor liquid crystal display includes a lower substrate, a thin film transistor, as a switching device, formed on the lower substrate, an upper substrate opposite the lower substrate, a color filter of red, green and blue formed on the upper substrate and a liquid crystal sealed within a cavity defined by both substrates.
FIG. 1 is a cross section showing a conventional thin film transistor liquid crystal display (TFT LCD).
An etch stopper inverse staggered type (7-mask process) thin film transistor 15 is disposed on a portion of a lower substrate 1 and a pixel electrode 8 is disposed on the other portion of the lower substrate 1. The pixel electrode is of ITO. A passivation layer 9 for protecting the TFT 15 is arranged on the TFT 15. The TFT 15 has a gate 2a, a source 7a and a drain 7b. A storage electrode 2b on the same plane as the gate 2a, the pixel electrode 8 and an insulating layer 3 interposed between the storage electrode 2b and the pixel electrode 8, form a capacitor 17. A black matrix 12 is disposed on a portion of the upper substrate 11 for preventing crosstalk in the liquid crystal display. The black matrix 12 is formed on a portion of the upper substrate corresponding to the TFT 15 and the capacitor 17. The color filter layer 13 of red, green and blue is disposed on another portion of the upper substrate which corresponds to the pixel electrode. A common electrode 14 is arranged on the black matrix 12 and the color filter 13. The common electrode 14 is of ITO. A numeral 4 indicates an active region, a numeral 5 indicates an etch stopper and a numeral 6 indicates an ohmic resistance contact layer.
In order to manufacture such TFT LCD in one production line, the TFT 15 is formed on the portion of the lower substrate 1. During the formation of the TFT 15 before forming the source 7a and the drain 7b, the pixel electrode 8 is formed on the other portion of the lower substrate 1. Thereafter, the passivation layer 9, for protecting the TFT 15 is formed thereon. In another production line, the black matrix 12 is formed on a portion of the upper substrate 11 corresponding to the TFT 15 and the capacitor 17. The color filter layer 13 is formed on another portion of the upper substrate 11 corresponding to the pixel electrode 8. Then the common electrode 14 is formed over the resultant portion in which the black matrix 12 and the color filter 13 are provided.
According to the above described manufacturing method, two production lies are required to fabricate the TFT LCD, one for formation of the TFT 15 on the lower substrate 1 and the other for formation of the color filter layer 13 and the black matrix 12 on the upper substrate 11. Investment and production costs are thus excessive.
In addition, the conventional liquid-crystal panel where the color filter 13 and the black matrix 12 are disposed on the upper substrate 11 facing an active-matrix substrate 1 must be manufactured with a given margin for alignment error which may occur during assembly. It has been, therefore, difficult to ensure the maximum area of the pixel opening (opening ratio).